Astronomers Find Two Galaxy Systems Like Our Own

One of two similar galaxy systems to the Milky Way's. The larger galaxy is called GAMA202627 and has two big companions. Image: Aaron Robotham/ICRAR/St Andrews/GAMA

By Liat Clark, Wired UK

In the quest to prove we’re not alone in the universe astronomers have at least proved the Milky Way isn’t, according to a paper revealing the existence of two galaxy systems almost exactly like ours.

[partner id=”wireduk”]The team made the discovery by making use of the Galaxy And Mass Assembly survey (GAMA), a project that brings together data from six wide-field survey telescopes to build a detailed 3D map of galaxies in the local universe. Using this map the astronomers identified, for the first time, that 14 galaxies similar to the Milky Way are also accompanied by dwarf galaxies similar to the Large and Small Magellanic Clouds orbiting our galaxy. Of these, lead researcher Aaron Robotham of the International Centre for Radio Astronomy Research (ICRAR) said in a press release that two are “an almost exact match.”

“We’ve never found another galaxy system like the Milky Way before, which is not surprising considering how hard they are to spot,” said Robotham, who works at the University of Western Australia and the University of St Andrews in collaboration with the ICRAR, in the release. “It’s only recently become possible to do the type of analysis that lets us find similar groups.

“Everything had to come together at once: we needed telescopes good enough to detect not just galaxies but their faint companions, we needed to look at large sections of the sky, and most of all we needed to make sure no galaxies were missed in the survey,” he said in the release

The comprehensive study proves something astronomers had long suspected and only come close to proving with simulators — our galaxy system is indeed a rarity, with the number of formations almost exactly the same amounting to just 0.4 percent of the hundreds of thousands of galaxies present in the local universe. What’s unusual about the Milky Way is that the Large and Small Magellanic Clouds orbit it very closely (they can clearly be seen in the night sky in the southern hemisphere), while at the same time they are both relatively enormous. The Milky Way is about 100,000 light years in diameter, while the Large and Small Magellanic Clouds are 14,000 and 7,000 across respectively. Evidence suggests the latter have both been distorted and their evolution disrupted because of their proximity to the Milky Way, and vice versa.

“The galaxy we live in is perfectly typical, but the nearby Magellenic Clouds are a rare, and possibly short-lived, occurrence. We should enjoy them whilst we can, they’ll only be around for a few billion more years,” said Robotham in the release.

Robotham and his team will study the two galaxies up close with telescopes at New South Wales and Chile, and will continue to contribute to GAMA which, Robotham told Wired.co.uk, already has data on 190,000 galaxies in the local universe. “We hope to get up to 250,000 to 300,000 redshifts by the end of the survey,” he said.

The paper detailing the finds was published in the August edition of the Monthly Notices of the Royal Astronomical Society.